JPH08308121A - Battery pack, method of controlling operation mode thereof, and electronic device - Google Patents

Abstract

(57) [Abstract] [Purpose] To prevent unnecessary power consumption in the battery pack. In the CPU 1, a data terminal DATAB for communicating with the load / charger 11 and terminals EB + and EB for supplying a current to the load / charger 11
When the − is normally connected to the load / charger 11, the connection terminal BATTINB connected to the load / charger 11
Is detected, and the supply of power to the current measuring unit 5, the voltage measuring unit 6, and the temperature measuring unit 7 is controlled according to the detection result.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery pack capable of exchanging data on the state of a secondary battery, a method of controlling its operation mode, and an electronic device.

[0002]

2. Description of the Related Art Recently, for example, an IC (In
Integrated circuit) and temperature sensor are built-in to monitor the status of the secondary battery (eg secondary battery voltage, charging / discharging current, temperature, etc.) and transfer data to / from a charger or computer load. A battery pack called Smart Battery or Intelligent Battery that exchanges is realized.

When such a battery pack is used, the charger or the load side can calculate the remaining capacity with relatively high accuracy based on the state of the secondary battery supplied from the battery pack. it can.

[0004]

By the way, when such a battery pack is attached to a load such as a computer, each block constituting the battery pack normally operates regardless of the power supply state of the computer. It was designed to do.

That is, even if the power of the computer is turned off, the battery monitoring IC in the battery pack, the temperature sensor, and the like operate, and so to speak, wasteful power is consumed. For this reason, there is a problem that the time for which the computer can be operated without a so-called AC (Alternating Current) adapter, that is, only with the battery pack (the usage time of the battery pack) is shortened.

The present invention has been made in view of the above circumstances, and is intended to prolong the usage time of a battery pack.

[0007]

The battery pack of the present invention comprises a + and-terminal for supplying a current to an electronic device, a communication terminal for communicating with the electronic device, and a + and-terminal. A connection terminal that is connected to the electronic device when the device is normally connected to the electronic device; and a setting unit that sets an operation mode corresponding to the voltages of the communication terminal and the connection terminal. .

The method of controlling the operation mode of the battery pack according to the present invention includes the + and − for supplying the electric current to the electronic equipment.
A terminal and a communication terminal for communicating with an electronic device,
When the + and-terminals are properly connected to the electronic device,
A method for controlling an operation mode of a battery pack that is equipped with an electronic device and that is connected to the electronic device and that operates as a power supply for the electronic device. The method detects voltage of a communication terminal and a connection terminal, and detects the voltage. The feature is that the operation mode is set according to the result.

In the electronic apparatus of the present invention, the + and-terminals for inputting the current from the battery pack, the communication terminals for communicating with the battery pack, and the + and-terminals are normally connected to the battery pack. A connection terminal that is connected to the battery pack when connected, and a detection unit that detects the state of the power supply and that sets the output voltage of the communication terminal to a constant value according to the detection result, are connected. It is characterized in that a voltage of a predetermined level is output from the terminal.

[0010]

In the battery pack of the present invention, electric current is supplied to the electronic device via the + and-terminals, and communication with the electronic device is performed via the communication terminal. The connection terminal is connected to the electronic device when the + and-terminals are normally connected to the electronic device, and the setting means sets the operation mode in accordance with the voltages of the communication terminal and the connection terminal. Has been done.

In the method of controlling the operation mode of the battery pack according to the present invention, the communication terminal for communicating with the electronic device and the + and-terminals for supplying a current to the electronic device normally operate in the electronic device. When connected, the voltage of the connection terminal connected to the electronic device is detected, and the operation mode is set according to the detection result.

In the electronic device of the present invention, + and-
The current from the battery pack is input through the terminal, and the communication with the battery pack is performed through the communication terminal. The connection terminal that outputs a voltage of a predetermined level is connected to the battery pack when the + and-terminals are normally connected to the battery pack, and the detection means detects the state of the power supply and outputs the detection result. Correspondingly,
The output voltage of the communication terminal is designed to be a constant value.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the configuration of an embodiment of a battery pack to which the present invention is applied, and a charger operating with the battery pack as a power source, for example, a load of a portable computer or the like, or a charger for charging the battery pack. 2 shows an example of the configuration of the load / charger (electronic device) 11 of FIG.

The battery pack is a battery pack (intelligent battery) having a communication function as described above, and a secondary battery E and a CPU (Central Proccessor Uni).
t) 1 (setting means), FET (field effect transistor)
It is composed of (N-channel MOS FETs) 3 and 4, and has terminals EB + (+ terminals), DATAB (communication terminals), BATTINB (connection terminals), and EB- (-terminals).

The secondary battery E is, for example, a lithium ion type battery, its + terminal is connected to the terminal EB + of the pack (battery pack), and its-terminal is in series with the secondary battery E. It is connected to the terminal EB- of the pack through the FETs 4 and 3 connected to. Therefore, 2
The discharge current of the secondary battery E flows through the terminals EB + and EB− (the discharge current is supplied to the load through the terminals EB + and EB−), and the charging current for the secondary battery E is also at this terminal. It is designed to flow through EB + and EB-.

The CPU 1 has a voltage of the secondary voltage E (hereinafter, appropriately referred to as a battery voltage) (this is a voltage measuring unit 6 which will be described later).
Voltage supplied to the gates (G) of the FETs 3 and 4 in accordance with
4 is turned on / off. Furthermore, C
PU1 is the data terminal (communication terminal) DATA of the pack
It is also connected to B and performs a predetermined process in accordance with the data transmitted via the data terminal DATAB, or a current measuring unit 5, a voltage measuring unit 6, or a temperature measuring unit 7 described later. The information (state of the secondary battery E) such as the voltage, the charging / discharging current, or the temperature of the secondary battery E, which is respectively supplied from, is output via the data terminal DATAB. That is, the CPU 1 can communicate with the load / charger 11 connected to the battery pack via the data terminal DATAB.

Further, the CPU 1 has terminals EB + and EC.
-Is normally connected to the load / charger 11 when the load / charger 11 has a connection terminal BATT
It is also connected to a connection terminal BATTINB that is connected to INC, and is also configured to set the operation mode of the battery pack in accordance with the voltage of this connection terminal BATTINB and the above-mentioned data terminal DATAB.

Here, the power terminal (terminal for supplying power to the CPU 1) or the ground terminal (not shown) of the CPU 1 is, for example, a connection point between the terminal EB + and the + terminal of the secondary battery or the FET 3. It is connected to the connection point between the source and the source of the FET 4, and the CPU 1 is connected to the secondary battery E, or from the load / charger 11 when the load / charger 11 is connected to the battery pack as a charger. , The power is supplied. The voltage (potential difference) between the power supply terminal and the ground terminal of the CPU 1 is set to a predetermined constant voltage (a voltage suitable for the power supply of the CPU 1) by a circuit (not shown).

The drain (D) of the FET3 has a terminal EB-
, And its source (S) is connected to the source of the FET 4. The drain of the FET 4 is connected to the-terminal of the secondary battery E. In addition, in FET3,
A parasitic diode 3A is formed between the source and the drain in a direction in which a charging current of the secondary battery E flows (thus, in a direction in which a discharging current of the secondary battery E does not flow).
In addition, the FET4, between its source and drain,
In the direction in which the discharge current of the secondary battery E flows (therefore, in the direction in which the charging current of the secondary battery E does not flow), the parasitic diode 4
A is formed.

The current measuring unit 5 detects (measures) the discharge current from the secondary battery E and the charging current to the secondary battery E, and C
It is designed to be supplied to PU1. Voltage measuring unit 6
Detects (measures) the battery voltage (voltage of the secondary battery E),
It is designed to be supplied to the CPU 1. Temperature measuring unit 7
Measures the temperature of the secondary battery E and supplies it to the CPU 1.

The current measuring unit 5, the voltage measuring unit 6, and the temperature measuring unit 7 are supplied with power in the same manner as in the CPU 1. Also, CPU
1 can control the supply of power to the current measuring unit 5, the voltage measuring unit 6, and the temperature measuring unit 7.

On the other hand, the load / charger 11 comprises a processing unit 11A (detection means) having a function as a load or a charger and a power switch 12, and the load / charger 11
On the other hand, when the battery pack is properly attached, the terminals EB +, DATAB, BATTIN of the battery pack
It has terminals EC + (+ terminal), DATAC (communication terminal), BATTINC (connection terminal), and EC- (-terminal) connected to B and EB-, respectively.

The processing section 11A has terminals EC + and EC-.
Therefore, when the load / charger 11 operates as a load, the discharge current of the secondary battery E flows through the terminals EC + and EC− (the discharge current from the battery pack is (Input via EC + and EB-), the processing unit 11A operates by using this current (discharge current of the secondary battery E) as a power source. Further, when the load / charger 11 operates as a charger, the processing unit 11A supplies the charging current to the secondary battery E,
It is adapted to be supplied via terminals EC + and EC-.

Further, the processing section 11A has a data terminal DAT.
It is also connected to AC, and communicates with the battery pack (CPU 1) via this data terminal DATAC. That is, the processing unit 11A transmits a command requesting the state of the secondary battery E to, for example, the CPU 1 via the data terminal DATAC, and the secondary battery transmitted from the CPU 1 via the data terminal DATAC. It is designed to receive the status of.

The power switch 12 is adapted to be operated when the power of the load / charger 11 is turned on / off. Note that the processing unit 11A uses, for example, the power switch 12
By detecting the operation state of, the power supply state is detected (whether the power supply is in the ON state or the OFF state is detected), and the output of the data terminal DATAC corresponding to the detection result. The voltage is set to a constant value (H level (for example, 5
V) or L level (for example, 0V).

A predetermined voltage appears (is output) at the connection terminal BATTINC. That is, in this embodiment, the connection terminal BATTIN
C is connected to the terminal EC + via the resistor R,
Accordingly, when the battery pack is properly attached to the load / charger 11 (when the terminal EB + or EB− of the battery pack is connected to the terminal EC + or EC− of the load / charger 11, respectively), the connection terminal BATTINC
Is the voltage at the terminal EB + of the battery pack
It is made to appear via + and the resistance R.

Next, the operation will be described. CPU
No. 1 applies the L level to the gates of the FETs 3 and 4 when a predetermined voltage is not applied to the terminal BATTINB, thereby turning off the FETs 3 and 4. In such a state, when the battery pack is normally attached to the load / charger 11, that is,
Battery pack terminals EB +, DATAB, BATTI
NB, EB- and terminals EC +, DA of the load / charger 11
When TAC, BATTINC, and EC- are respectively connected, the voltage (battery voltage) of the terminal EB + is output from the connection terminal BATTINB via the terminal EC +, the resistor R, and the connection terminal BATTINC.

This voltage is detected by the CPU 1 and C
When PU1 detects that a predetermined voltage is output from the connection terminal BATTINB, PU1 applies an H level to the gates of FETs 3 and 4, thereby turning on FETs 3 and 4. Therefore, when the load / charger 11 is loaded and the battery pack is properly installed, the secondary battery E, the terminals EB + and EC +, the processing unit 11A, the terminals EC−, EB−, and the FET3 (drain)・
A discharge current flows through the path between the source) and FET4 (between the source and the drain).

At this time, the CPU 1 monitors the battery voltage supplied from the voltage measuring unit 6, and this is the predetermined first reference voltage (the voltage at which the secondary battery E may be in an overdischarged state). When it becomes smaller, the gate of FET3
The L level is applied to turn off the FET3.
Since the parasitic diode 3A of the FET 3 is connected in the direction in which the charging current flows, that is, the direction in which the discharging current does not flow, when the FET 3 is turned off, the discharging current is cut off. This prevents over-discharge.

In this state, when the load / charger 11 is used as a charger, the processing section 11A, the terminal EC +,
EB +, secondary battery E, FET4, parasitic diode 3A,
A charging current flows through the paths of the terminals EB− and EC−, whereby charging of the secondary battery E is started. However, in this case, in the parasitic diode 3A, when a voltage of a certain level is applied to the gate in comparison with the source-drain of the FET3 (FET3 (the same applies to the FET4), the ON resistance thereof becomes a small value. Therefore, the voltage drop between the source and drain is very small), and a large voltage drop of about 0.6 to 0.8 V occurs, so that efficient charging cannot be performed.

Therefore, when the charging is started, that is, when the load / charger 11 is used as a charger, the CPU 1 detects a voltage drop (for example, a voltage drop of about 1 V) caused by the charging, and the voltage is detected. When the drop is detected, the H level is forcibly applied to the gate of the FET3 to turn on the FET3. As a result, the processing unit 11A and the terminals EC +, E
B +, secondary battery E, FET4, FET3, terminal EB-,
A charging current flows through the path of EC−, and efficient charging is performed.

Applying the H level to the gate of the FET3 is performed by the CPU1 via the connection terminal DATAB.
On the other hand, it is designed to be performed only when a predetermined voltage is applied. That is, the CPU 1 uses the connection terminal D
When the predetermined voltage is not applied to the ATAB, specifically, for example, the battery pack is not properly attached to the load / charger 11, and thus the terminals BATTINC and B
If the ATTINB is not connected, FE
The H level is not applied to the gate of T3. Therefore, in this case, the battery pack is in a state in which it cannot perform discharging but can only perform charging.

While charging, the CPU 1 monitors the battery voltage as in the case of discharging, and this monitors the predetermined second reference voltage (the secondary battery E becomes overcharged). If the voltage becomes larger than the potential voltage), the L level is applied to the gate of the FET4, thereby turning off the FET4. Since the parasitic diode 4A of the FET 4 is connected in the direction in which the discharging current flows, that is, the direction in which the charging current does not flow, the charging current is cut off when the FET 4 is turned off. This prevents overcharging.

In this state, when the load / charger 11 connected between the terminals EB + and EB- is loaded again, the secondary battery E, the terminals EB +, EC +,
A discharge current flows through the path of the processing unit 11A, the terminals EC−, EB−, the FET 3, and the parasitic diode 4A, and the discharge is started. However, in this case, the parasitic diode 4A
Then, since a large voltage drop occurs like the parasitic diode 3A described above, efficient discharge cannot be performed.

Therefore, when the discharge is started, that is, when the load / charger 11 is loaded, the CPU 1 detects, for example, a voltage drop (for example, a voltage drop of about 0.4V) caused by the load, and When a voltage drop is detected, FET4
The H level is forcibly applied to the gate of the FET to turn on the FET 4 (note that applying the H level to the FET 4 also applies a predetermined voltage to the connection terminal DATAB as in the case of the FET 3 described above. It is possible to prevent (prohibit) the operation when the voltage is not applied). Thereby, as described above, the secondary battery E, the terminals EB +, EC +, the load / charger 11, the terminals EC-, EB.
A discharge current flows through the path of −, FET3, and FET4, and efficient discharge is performed.

As described above, the battery pack is
When normally connected to the load / charger 5, the data terminal DATAC is connected between the processing unit 5A and the control circuit 1.
Data can be exchanged via the and DATAB. That is, when the battery pack is normally connected to the load / charger 5,
The processing unit 5A can be made to request the control circuit 1 for information regarding the state of the secondary battery.
In addition, the state of the secondary battery E can be transmitted to the processing unit 5A in response to a request from the processing unit 5A.

Next, the battery pack is loaded into the load / charger 1
If the battery pack 1 is not properly mounted, the connection terminal BATTINB of the battery pack and the connection terminal BATTINC of the load / charger 11 are not connected. Therefore, in this case, the predetermined voltage does not appear at the connection terminal BATTINB, and as a result, the CPU 1 does not detect the predetermined voltage through the connection terminal BATTINB.

When the CPU 1 cannot detect the predetermined voltage via the connection terminal BATTINB, the FE
Since the H level is not applied to the gate of T3 (FET3
FET3 does not turn on, and the parasitic diode 3A
Is formed in a direction in which the discharge current does not flow, and therefore, for example, erroneously, the terminal EB + or EB− of the battery pack and the terminal EC− or EB + of the load / charger 11 are erroneously detected.
The discharge current does not flow even when and are connected.

Therefore, it is possible to prevent the processing section 11A from being damaged, for example, by applying a voltage in the opposite direction to the voltage that should be originally applied to the processing section 11A.

In order to prevent the voltage opposite to the voltage to be originally applied from being applied to the processing section 11A, the shape of the battery pack and the load / charge of the part to which the battery pack is mounted are to be prevented. It is preferable that the shape of the battery 11 is such that the battery pack cannot be mounted on the load / charger 11 so that such a reverse voltage can be applied.

Next, the terminals EB + and EB of the battery pack
When-and, for example, are directly connected, the CPU 1 does not detect a predetermined voltage via the connection terminal BATTINB in the same manner as in the case described above, so that the FET 3 is kept off. Therefore, in this case also, the discharge current does not flow,
As a result, it is possible to prevent the battery pack from being damaged due to a short circuit between the terminals EB + and EB-.

It should be noted that, regardless of the voltage appearing at the connection terminal BATTINB, the FETs 3 and 4 are turned on / off in the CPU1.
Even when the off control is performed, when the terminals EB + and EB− are short-circuited, a large discharge current flows, so that the battery voltage drops, and as described above, the FET3 is turned off, which interrupts the discharge current. To be done. Therefore,
This also prevents damage to the battery pack, but in this case, a large discharge current will flow for a short time. On the other hand, according to the battery pack of FIG. 1, since such a large discharge current does not flow, damage to the battery pack can be prevented more effectively.

Next, the CPU 1 sets the operation mode of the battery pack in accordance with the voltages of the connection terminal BATTINB and the data terminal DATAB, as described above. The operation mode setting process by the CPU 1 will be described below with reference to the flowchart of FIG.

First, in step S1, the CPU 1 sets the operation mode to the low power consumption mode. That is, in step S1, the operation of each block constituting the battery pack excluding the minimum required block is stopped (set to a sleep state). In this embodiment, C
According to PU1, for example, the current measuring unit 5, the voltage measuring unit 6,
Also, the supply of power to the temperature measuring unit 7 is stopped.

Then, in step S2, the connection terminal B
It is determined whether the level of ATTINB is the H level. In step S2, the connection terminal BATTIN
When it is determined that the B level is not the H level, that is, when the CPU 1 cannot detect the predetermined voltage via the connection terminal BATTINB, the process returns to step S1. Note that, in step S1, no particular process is performed if the operation mode is already the low power consumption mode. That is, in step S1, the process of changing (setting) the operation mode to the low power consumption mode is performed only when the operation mode is not the low power consumption mode (a normal mode described later).

Therefore, the battery pack is the load / charger 5
If the battery pack is not attached to the battery pack, or if it is not attached to the battery pack even if it is not normally installed, the operation mode of the battery pack is set to the low power consumption mode. Therefore, useless power consumption can be prevented.

On the other hand, in step S2, the connection terminal B
When it is determined that the level of ATTINB is H level, that is, the battery pack is normally attached to the load / charger 11, and the CPU 1 determines that the connection terminal BATTIN
When the predetermined voltage can be detected via B, the process proceeds to step S3, and a variable C for measuring time is set to an initial value, for example, 0.

Then, in step S4, it is determined whether or not the level of the data terminal DATAB has changed. When it is determined in step S4 that the level of the data terminal DATAB has changed, that is, from the processing unit 11A,
CP via data terminals DATAC and DATAB
If some data or command is transmitted to U1, and therefore the power supply of the load / charger 11 is in the ON state, the process proceeds to step S7 and the operation mode is set to the normal mode.

That is, in step S7, among the blocks constituting the battery pack, the operation of the operation-stopped one (the one in the sleep state) is started. In this embodiment, the CPU 1 controls the current measuring unit 5,
The power supply to the voltage measuring unit 6 and the temperature measuring unit 7 is started. Note that in step S7, similar to the case in step S1, if the operation mode is already the normal mode, no particular process is performed. That is, in step S7, a process of changing (setting) the operation mode to the normal mode is performed only when the operation mode is the low power consumption mode.

Therefore, in the state where the operation mode is the low power consumption mode, the processing section 11A requests the CPU 1 via the data terminals DATAC and DATAB to transmit, for example, the state of the secondary battery E. In this case, the operation mode is set to the normal mode, and the operations of the current measuring unit 5, the voltage measuring unit 6, and the temperature measuring unit 7 are thereby started. Then, the state of the secondary battery E output from the current measuring unit 5, the voltage measuring unit 6, and the temperature measuring unit 7 is transmitted to the load / charger 1.

On the other hand, if it is determined in step S4 that the level of the data terminal DATAB has not changed, the process proceeds to step S5 and the variable C is incremented by 1. Then, in step S6, it is determined whether or not the variable C is larger than a predetermined number N. When it is determined in step S6 that the variable C is not larger than the predetermined number N, that is, in step S2, the connection terminal BATTINB
If the time corresponding to the predetermined number N has not elapsed since the level of the data terminal DATAB has not changed since it is determined that the level is the H level, the process returns to step S4.

When it is determined in step S6 that the variable C is larger than the predetermined number N, that is, after the level of the connection terminal BATTINB is determined to be H level in step S2, the level of the data terminal DATAB is determined. If the time corresponding to the predetermined number N has elapsed without changing, the process returns to step S1. Therefore, in this case, when the operation mode is the normal mode, the operation mode is changed to the low power consumption mode in step S1.

As described above, the processing section 11A detects the state of the power source by monitoring the operating state of the power switch 12, and when the power source is off, the level of the data terminal DATAC is detected. Is set to a predetermined constant level (for example, H level of H and L levels). Therefore, the level of the data terminal DATAC is H while the power of the load / charger 11 is off.
Since the level remains unchanged, the operation mode of the battery pack is set to the low power consumption mode even if it is normally attached to the load / charger 11.

Therefore, it is possible to prevent unnecessary power consumption in the battery pack.

Even if the load / charger 11 is powered on, unless the processing unit 11A requests the CPU 1 to transmit the status of the secondary battery E, the data terminal D
The ATAC level does not change. Therefore, even if the load / charger 11 is powered on, the CPU 1 and the processing unit 1
When the communication with the 1A is not performed for a predetermined time (a time corresponding to the predetermined number N), the operation mode is set to the low power consumption mode.

As described above, when the level of the connection terminal BATTINB is a predetermined level (H level in this embodiment) and the level of the data terminal DATAB changes,
Set the operation mode to normal mode and connect the terminal BATTINB
Voltage of the data terminal DATAB
When the level of has not changed for a predetermined time and when the level of the connection terminal BATTINB is a level other than the predetermined level, the operation mode is set to the low power consumption mode. When not attached to the charger 11, or even when attached, when the power of the load / charger 11 is turned off, or when communication is not performed between the CPU 1 and the processing unit 11A, etc. It is possible to prevent wasteful power consumption when it is not necessary to operate the current measuring unit 5, the voltage measuring unit 6, and the temperature measuring unit 7. Further, as a result, the usage time of the battery pack can be extended as compared with the conventional case.

In this embodiment, the rechargeable battery E is a lithium-ion type battery, but the rechargeable battery E may be of another type (for example, a lead battery or a Nickd type battery). Is possible.

Further, in this embodiment, the load / charger 11
Although a predetermined voltage appears at the terminal BATTINC by connecting the terminals EC + and BATTINC of the terminal B through the resistor R, in order to make the predetermined voltage appear at the terminal BATTINC, other processing, for example, Part 1
A predetermined voltage may be output from 1A to the terminal BATTINC.

Further, in this embodiment, the FET 3 or 4 turns on / off the discharge current or the charge current, respectively.
It was turned off, but the discharge current and charge current were turned on /
As the element to be turned off, any element that functions as a switch can be used in addition to the FET.

Further, in the present embodiment, the FETs 3 and 4 are directly controlled by the CPU 1, but in addition to this, for example, the processing unit 11A is used to control the FETs 3 and 4 through the data terminals DATAC and DATAB and the CPU 1.
4 can also be controlled.

When the CPU 1 and the processing unit 11A are not communicating with each other, the processing unit 11A has a data terminal DATAC, and when the power is on, the processing unit 11A has one of the H and L levels. For example, an H level can be output, and an L level can be output when the power is off. In this case, in the CPU 1, when the voltage of the data terminal DATAB does not change for a predetermined time, depending on whether the level of the data terminal DATAB is the H level or the L level, the load / charger 11 is powered on. The state can be recognized.

[0062]

According to the battery pack and the method of controlling the operation mode thereof of the present invention, the communication terminal for communicating with the electronic device and the + and-terminals for supplying a current to the electronic device are electronic. When the device is properly connected, the voltage of the connection terminal connected to the electronic device is detected, and the operation mode is set according to the detection result, thus preventing unnecessary power consumption. Is possible.

According to the electronic device of the present invention, the state of the power supply is detected, and the output voltage of the communication terminal for communicating with the battery pack is set to a constant value according to the detection result. Further, the connection terminal that outputs a predetermined level is connected to the battery pack when the + and-terminals are normally connected to the battery pack. Therefore, on the battery pack side, it is possible to recognize the connection state with the electronic device and the state of the power supply thereof based on the voltages of the communication terminal and the connection terminal.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of a load / charger 11 as a battery pack and an electronic device to which the present invention is applied.

FIG. 2 is a flowchart illustrating an operation of CPU 1 in FIG.

[Explanation of symbols]

 1 CPU 5 Current Measuring Section 6 Voltage Measuring Section 7 Temperature Measuring Section 11 Load / Charger 11A Processing Section 12 Power Switch

Claims (5)

[Claims] 1. A battery pack that is mounted on an electronic device and operates as a power source thereof, comprising: + and-terminals for supplying a current to the electronic device; and a communication terminal for performing communication with the electronic device. A setting for setting an operation mode corresponding to the connection terminal connected to the electronic device when the + and-terminals are normally connected to the electronic device and the voltages of the communication terminal and the connection terminal And a battery pack. 2. The setting means sets the operation mode to a normal mode when the voltage at the connection terminal is at a predetermined level and the voltage at the communication terminal changes, and the voltage at the connection terminal is at the predetermined level. And the voltage of the communication terminal has not changed for a predetermined time, and the voltage of the connection terminal is a level other than the predetermined level, the operation mode is set to the low power consumption mode. The battery pack according to claim 1, wherein: 3. The + and-terminals for supplying a current to the electronic device, the communication terminal for communicating with the electronic device, and the + and-terminals are normally connected to the electronic device. A method of controlling an operation mode of a battery pack that is equipped with a connection terminal that is connected to the electronic device and that is mounted on the electronic device and that operates as a power supply thereof, wherein the voltage of the communication terminal and the connection terminal is A method of controlling an operation mode of a battery pack, which comprises detecting and setting an operation mode in accordance with the detection result. 4. An electronic device that operates by receiving current supply from a communicable battery pack, and performs communication with the + and-terminals for inputting current from the battery pack, and with the battery pack. And a connection terminal for connecting the battery pack to the battery pack when the + and-terminals are normally connected to the battery pack, and a power supply state is detected. An electronic device, comprising: a detecting unit configured to set an output voltage of the communication terminal to a constant value, wherein a voltage of a predetermined level is output from the connection terminal. 5. The electronic device according to claim 4, wherein the connection terminal is connected to the + terminal.